patch 8.2.4111: potential proglem when map is deleted while executing

Problem:    Potential proglem when map is deleted while executing.
Solution:   Reset last used map pointer when deleting a mapping.
diff --git a/src/version.c b/src/version.c
index b658ec7..ec1ba92 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4111,
+/**/
     4110,
 /**/
     4109,